This Oct. 14, 2015 file photo shows the Food and Drug Administration campus in Silver Spring, Md. On Thursday, June 8, 2017, the FDA said it has asked Endo Pharmaceuticals to stop selling its reformulated, extended-release painkiller, Opana ER.

This Oct. 14, 2015 file photo shows the Food and Drug Administration campus in Silver Spring, Md. On Thursday, June 8, 2017, the FDA said it has asked Endo Pharmaceuticals to stop selling its reformulated, extended-release painkiller, Opana ER.

(Andrew Harnik / AP)

Linda A. JohnsonAP Medical Writer

U.S. regulators want a narcotic painkiller involved in the opioid epidemic off the market amid data showing people continue to abuse it.

The Food and Drug Administration said Thursday it has asked Endo Pharmaceuticals to stop selling its reformulated, extended-release painkiller, Opana ER, after concluding the drugs's risks outweigh its benefits.

It's the first time the FDA has asked a drugmaker to remove an opioid painkiller from the market. The agency said it has seen a "significant shift" from people crushing and snorting Opana ER to get high to injecting it.

Endo said in a statement it's "reviewing the request and is evaluating the full range of potential options."

Wall Street responded quickly with a sell-off, and Endo shares plunged 13.4 percent to $11.93 in trading after U.S. markets closed.

The FDA move comes after advisers, reviewing the safety of Opana ER at a March hearing, voted 18-8 against keeping it on the market.

Besides contributing to overdoses, abuse of Opana ER was blamed for a 2015 outbreak of HIV and hepatitis C in southern Indiana linked to sharing needles, according to the FDA.

"We are facing an opioid epidemic - a public health crisis, and we must take all necessary steps to reduce the scope of opioid misuse and abuse," FDA Commissioner Dr. Scott Gottlieb said in a statement. "We will continue to take regulatory steps when we see situations where an opioid product's risks outweigh its benefits."

About 2 million Americans are addicted to prescription opioids, and 91 die every day from overdosing on a painkiller or much-cheaper heroin.

Endo first got U.S. approval for its extended-release opioid, Opana ER, in 2006. It reformulated that drug in 2012 and claimed the changes made it harder to manipulate physically or chemically to abuse it. Endo tried to persuade FDA officials that the new formulation was abuse-resistant, which likely would have given the product a marketing advantage in the crowded, lucrative category of opioid painkillers.

The FDA didn't agree, refusing to let Endo market the new formulation as abuse deterrent when it granted approval for sales several years ago.

If Endo doesn't comply with the FDA's request to stop selling Opana ER, the agency can hold a hearing and start a formal process for rescinding its approval.

According to the FDA, there are no generic versions of the reformulated Opana ER on the market. However, generic versions of both the original Opana ER and the original immediate-release version, called oxymorphone ER, are on sale.

Those generic products might also face action by the FDA, which said it is "assessing the latest available data on abuse patterns."

Endo Pharmaceuticals makes generic pills and specialty drugs, which generally are expensive medicines for complex disorders. It's part of Endo International plc, which is based in Dublin, Ireland, and has U.S. headquarters in the Philadelphia suburb of Malvern.

Endo had about $4 billion in revenue last year, only $159 million of that from Opana.